Whether or not this is true, many of us have experienced a shaky voice during times of anxiety. It can happen in any stressful situation, but it is most pronounced when we are called upon to give a speech.

According to Psychology Today, the fear of public speaking stems from a fear of social evaluation. When you speak in front of others, people are judging you and how you perform. This leads to a stress response because the prospect of looking like a fool puts your body in panic mode.

So what is the actual science behind that shaky voice?

It’s related to the body’s fight-or-flight response. Evolutionary biology tells us that the goal of any living creature is to survive long enough to reproduce. In order to survive, we have evolved defence mechanisms that allow us to become aware of any immediate danger and act accordingly.

Fight or flight is one such mechanism and it is triggered by your sympathetic nervous system. After perceiving danger, your sympathetic nervous system tells your brain to release adrenaline. This hormone increases your heart rate and makes you faster, but also has side-effects such as a dry mouth, sweating, and shakiness of the hands or voice.

Back when we lived in caves, life was different. Our fight-or-flight response would have only kicked in when a lion or bear showed up. However, today we are surrounded by different kinds of stresses related to the trappings of modern life.

At least he never had to give a PowerPoint presentation.

So what can you do about it?

Just as we have a sympathetic nervous system that amps us up, we also have another mechanism to bring us back down.

At the core of this is the vagus nerve. Vagus is Latin for ‘wandering’, and this nerve has this name because of its multiple branches that wander from the lower parts of your abdomen all the way up to your brain.

One of the jobs of the vagus nerve is to send your noggin a steady stream of info about what your body is up to. It is so important that scientists have called it a “second brain” and believe it is responsible for much of what we call “gut feelings” (now you can say “I have to trust my vagus nerve on this one”).

The vagus nerve is also the commander of the parasympathetic nervous system, which causes your body to slow down after you have been in a fight-or-flight situation. It takes us into ‘rest and digest’ mode, bringing your body down into a relaxed state.

In other words, the vagus nerve is the thing that tells the brain “you are safe now, please return my body to normal” after a moment of stress or danger.